Ben 10 - The Crimson hero
by berserkerzero7
Summary: Our Alien Hero Ben 10 was approached by Paradox with two people he never met, now he must fight in a world full of devils, angels, gods and dragons to save their doomed world by a threat Ben thought he destroyed long ago.
1. Chapter 1

I do not own Ben 10 and Highschool DxD.

All are owned by their respected owners.

All right guys this is my first Fanfiction and I hope you will enjoy it.

Okay I just want to point out the plot and timeline

First off the plot will follow DxD plotline until the Rating game of Rias vs Sona and there, it will diverge with my own story and will resume in some point in time.

Secondly the Ben I'll use in my story will be from Omniverse but he will have the new omnitrix with the ultimate system and if you're curious how you'll find out within this chapter. Also the time line with Ben will be about after the episode he defeated malware in Galven Prime.

Thirdly Ben will have accesses to some degree with his anodite within the first few chapters and will continue to grow until he can transform to his full anodite form due to the exposure to the magic on the DxD universe.

Almost forgot the description/appearance I'll be using for the character of Ben 10 will be of UA.

So on with the story.

Ben 10 the Crimson Hero

Chapter 1: The Meeting that should not be.

**Bellwood – Mister Smoothies**

It was just another day for our alien hero Ben Tennyson,

Wielder of the most powerful device in the universe the omnitrix. The omnitrix, a level 20 alien device created by the smartest alien in 5 galaxies, Azmuth of the Galven. Ben was just having his 10th smoothies for the day when suddenly a blue vortex appeared right next to him.

(?) Well hello Ben, how are you?

Ben faced the being that appeared out of nowhere, yet he knew too well who he was. The man appeared to be of British origin, he was in his late 40s or 50s wearing a plane lab coat, black pants and goggles' hanging around his neck.

(Ben) Pro Professor Paradox!?

Professor Paradox the Immortal time walker who had helped Ben with his many adventures and the adventure that he will make.

(Ben) Professor is their another universe crisis or a world ending threat?

Ben said sarcastically while Paradox smiled in return.

(Paradox) Oh and what gave you that conclusion.

(Ben) Well that's always the reason you come to me, I 'am I right?

Paradox just laughs at Ben's declaration on how right he was.

(Paradox) Yes you're right Ben about the crisis but it's not in our own dimension.

(Ben) Huh?

(Paradox) They will explain it in more detail.

At the same moment another vortex appeared and two figures step out of the said vortex.

One of the two being was handsome and young, having the appearance of a man in his early 20's with shoulder length crimson red hair and blue-green eyes. The other being was a is a beautiful girl with long, black hair tied in twin ponytails and blue eyes with a child-like body and big….BREAST!

(Ben) **What the hell is with those BREASTS!**

Ben shouted in his head with shock and disbelief.

(?) Greeting's mighty Ben Tennyson I' am Sirzechs Lucifer one of the Four Great Satan's and the one next to me is Serafall Leviathan also one of the Four Great Satan's.

The Red headed man politely bowed and Ben did the same thing.

(Ben) Same here Sirzechs. "**What does he mean mighty?"**

Then suddenly Serafall ran towards Ben and hugged him like a teddy Bear.

(Serafall) Aw! He's so cute I can't help hug you all day Ben-tan!

(Ben) Ben-tan?

Ben was starting to turn red as a tomato with Serafall hugging him while oblivious to herself (yah right) she was grinding her breast on him, then without warning the omnitrix started to beep and the dial turning yellow.

(Omnitrix) "Unknown DNA detected" stated by the small device.

(Serafall/Ben) "Eh!?" both said in unison.

(Omnitrix) "Unknown Life form detected beginning scan"

Then a yellow beam of light enveloped Serafall from head to toe then vanished.

(Omnitrix) "Scan complete, unknown life form DNA recorded"

Then the omnitrix's dial returned to its normal shade of green.

(Serafall) Wha...What just happened?

Said the shocked devil.

(Ben) Well the omnitrix has the ability to scan new life forms that's not present in Primus.

(Sirzechs) Paradox-san you failed to mention the omnitrix is capable of such a feet.

Stated by the crimson haired man.

(Paradox) Cough! Well you didn't ask, Now with the Introductions are over we must be heading to Galven prime.

(Serafall) AW! Para-tan (can't think of a better nick name) is so mean I want to keep hugging Ben-tan a little bit more.

(Ben) "**Para-tan? The hell is this nick names coming from?!"**

(Sirzechs) I would really want to meet this Azmuth, who created the omnitrix that can be rivaled with a Longinus.

Ben was in deep thought on who these people where they say they where called the four great Satan's but to Ben's knowledge Satan's are related to Akuma (Devils) and not just mere devils but Devil lords.

(Ben) Um Sirzechs can I ask you something?

(Sirzech) Yes?

(Ben) Are you and Miss Sera-

(Serafall) Levi-tan!

With that sudden declaration Ben almost fell over

(Ben) Huh?

(Serafall) "Call me Levi-tan" while she made those poses that Magical girl's cosplayer in Japan.

Ben's brain almost shutdown on how cute she looked

(Ben) Ri…Right.

(Serafall) "Say it" said in a cold manner that sent chills to Ben's spin

(Ben) Le…Le…Levi-tan…..

Then Serafall jump with glee like a school girl after hearing Ben saying that.

(Paradox) Well off we go.

**Galven Prime – Azmuth's main Lab**

Within the plant of Galven Prime resides Azmuth creator of the omnitrix. He usually looks grumpy or irritated.

*Flash Back*

Azmuth was doing his daily checkups with some of his creation when suddenly Paradox showed up much to his displeasure.

(Azmuth) "Time walker what business do you have with me now" said Azmuth with much irritation.

(Paradox) Ah Azmuth how have you been.

(Azmuth) I was in a fairly good mood….until you showed up.

Paradox just chuckled at his replay.

(Azmuth) So exactly why are you here.

(Paradox) Always straight to the point, you never change whatever time line I go.

Azmuth just remained silent at his remark.

(Paradox) "Azmuth" said Paradox with a voice full of plea that surprised Azmuth for all he knew about Paradox this was the first time Paradox used this tone of voice. "I need you to re equip the ultimate system to the omnitrix"

(Azmuth) "WHAT!" Retorted by the Galven. "You know how dangerous that feature is, and yet you!"

Paradox just kept quiet and listened to the little aliens ranting for a few minutes.

(Paradox) "Are you done?" said the time walker.

(Azmuth) "Yes" said the Galven while deeply breathing.

(Paradox) The Reason why I want you to return the ultimate system back in the omnitrix is simple, the crisis that Ben will face is more difficult than any of his past struggles combined he may die , he'll need all the power he can get.

Azmuth was rather skeptical at the time walker's claim but Azmuth knew one thing, Paradox was never wrong.

(Azmuth) Very well I shall reinstall the ultimate system.

With that said paradox smiled

(Paradox) Ah splendid I shall return here with Ben and a few other's in about a week tata.

(Azmuth) "Others? Wait Para!" before he could finish Paradox disappeared with the familiar blue light. "Sigh"

*Flash Back End*

Azmuth sighed for the 20th time today while finishing the final touches' with the ultimate system. Then a blue portal opened what came through it was Paradox and Ben Tennyson but Azmuth saw two other unfamiliar people go through the portal.

(Azmuth) "I guess this are the others you mentioned before Paradox" said the little grey alien.

(Paradox) Azmuth let me introduce to you Sirzechs Lucifer and Serafall Leviathan.

(Sirzechs) "Greeting Sir Azmuth." Said the red headed devil.

(Serafall) "Hai Hai nice to meet you Frogy-chan!" (Again sorry for the lame nick name) said the cheerful girl.

(Ben) **"Ah shit" **Ben thought knowing Azmuth tendency to lose it when it comes to names, but to Ben's surprise expecting Azmuth to Lecture the air head devil he just sighed and looked at Paradox.

(Azmuth) "You didn't tell me they where devils Paradox." Said the smartest being in 5 galaxy's with a hint of amusement and curiosity.

(Sirzechs) "You know of our kind?" replied by the young red headed devil.

(Azmuth) Not only your kind but also the Angels and Fallens, they pass by this reality of earth from yours time to time, you knew this Paradox and didn't tell them.

(Serafall) "Can I ask you something?" said the cute little devil.

(Azmuth) "And that is?" replied by Azmuth.

(Serafall) "What did you do them?" said Serafall with atone of worry obviously for their own kind.

(Azmuth) To be frank some lived with the humans in earth without trouble but some caused some distress to the plumbers on earth and had to be reprimanded to Incarcecon.

(Serafall/Sirzechs) "Incarcecon?" both said in unison.

(Ben) "It's a prison organization which contains some of the worst criminals in the galaxy." Replied Ben feeling left out ( ).

(Serafall/Sirzechs) "…" both devil lords where silent not knowing what fate fell on their fallen kin.

(Paradox) I assure you both that they are not treated as bad as you think.

The news seemed to lift some distress from the 2 devils.

(Paradox) Now on to business, Azmuth is it ready?

(Azmuth) "Of course its finish! Who do you think I' am Paradox?!" shouted Azmuth.

(Paradox) Splendid, Ben would you come here for a moment.

(Ben) "Right" said Ben not sure why they were in Galven Prim in the first place. He then saw Azmuth brought out some short of alien USB then connected it to the side of the omnitrix.

(Omnitrix) "Uploading new system" declared by the omnitrix while sprouting out flashes of green light. "Upload complete Ultimate system now fully installed."

(Ben) "What! New ultimate system?!" Ben shouted with much surprise.

(Sirzechs) "Ultimate system?" asked the devil lord with much curiosity.

(Ben) "The Ultimate is feature of the omnitrix that allow me to lack of better words evolve my forms to its most battle prime state." Explained by our alien hero.

(Sirzechs) "Amazing" declared Sirzechs "Such power. Ajuka would have a field day if he ever gets his hands on the omnitrix."

(Azmuth) "Let him try, I doubt he can even pass the first safe guard of the omnitrix." Boast by the Galven genus.

(Ben) "Tsk" when Azmuth said that Ben remembered when he and Kevin tried hacking the omnitrix that resulted not only damaged the omnitrix but turned Kevin into a mutated freak again. He truly regretted on what he did. "Don't worry Azmuth I won't give him the chance even if he was a devil king or whatever."

Both Serafall and Sirzechs sweat drop anime style upon hearing Ben's declaration.

(Azmuth) See that you do Ben Tennyson.

(Paradox) "Now with all things settled lets…" Paradox was interrupted by Azmuth.

(Azmuth) Wait! I have something else for you Benjamin.

Azmuth walked up to some kind of vault and took out what appears to be a sword, immediately recognized the sword.

(Ben) Azmuth that's Sir George's sword.

Azmuth nodded to Ben's words.

(Azmuth) Ascalon.

Both Serafall and Sirzechs paled upon hearing the sword name.

(Serafall) "It can't be…" she whispered in a very low tone but Paradox heard and said "Yes Serafall it's the same sword from you world." Answered Paradox with assurance in his voice.

(Ben) Wait What! I thought Azmuth created the sword.

(Azmuth) The sword I gave to Sir George of or world was a replica of this sword I only kept the real one to further study it and gave it new features which in due time you will unlock it.

(Ben) But how can I keep carrying this sword a round.

(Azmuth) Just hold the sword and will it to disappear.

Ben concentrated with in his mind and to his surprise it did what he wanted to.

(Ben) "Wow" he said with amazement, then he noticed Serafall and Sirzechs they were very troubled about something. "What's wrong?" said with a worried tone.

(Sirzechs) Well Ben you see the holy power it's emitting is rather dangerous to use devils, it can kill use.

(Ben) Oh sorry.

(Sirzechs) No need for Apologies Ben.

(Ben) "At least I got some repellant for crazy girl over there." He said with a mischievous grin.

(Serafall) "Moh! Ben-tan is so mean, I just wanted to hug you that's all." Said the cute devil with fake tears.

(Paradox) "Now with all things settled we bet be on our way." With a flash of light every one minus Azmuth disappeared from the Lab.

Underworld- Gremory Territory

Now Ben saw he was in a place totally unfamiliar, he was in some short of garden that is covered with many flowers of different breed he didn't recognize with a huge mansion that he gasp at the sheer size but what alarmed him was the sky, it had no moon and purple in color that had countless stars.

(Ben) I take where in their home world huh?

(Sirzechs) Right you are Ben, Welcome to the Underworld Ben Tennyson.

Chapter-End


	2. Chapter 2

I do not own Ben 10 and Highschool DxD.

All are owned by their respected owners.

Alright chapter 2 is ready. FYI I 'am still trying to find a beta tester so please bare with me for a while and enjoy the story, oh thank you guys for the review's and favorites.

*Spoilers*

Well this chapter will just cover the explanation of the problem the DxD cast will face and Ben meeting Rias in Kuoh Academy, yah Ben WILL have the boosted gear so Issei won't be part of the story, sorry for the Issei fans who will be reading this.

*Spoiler End*

So on with the story

Chapter 2 - Crimson-Haired Ruin Princess meets the Protector of the Earth.

Previously:

Underworld- Gremory Territory

Now Ben saw he was in a place totally unfamiliar, he was in some short of garden that is covered with many flowers of different breed he didn't recognize with a huge mansion that he gasp at the sheer size but what alarmed him was the sky, it had no moon and purple in color that had countless stars.

(Ben) I take where in their home world huh?

(Sirzechs) Right you are Ben, Welcome to the Underworld Ben Tennyson.

*Story start*

(Ben) "Never thought hell will look like this, I was expecting it to be … terrifying." Ben said with a sarcastic tone.

(Sirzechs) "Not all things written or said are true Ben" Sirzechs replied.

(Ben) "True I 'am a perfect example of such things."

Then the large door of the Gremory manor suddenly opened and reveled was a beautiful woman appearing to be in her early twenties, with silver hair and matching eyes. Her hair, which flows all the way down to her back, features a long braid on each side with small blue bows at the ends, while the rest is let down, ending in twin braids, she was wearing a blue and white French maid outfit with long sleeves and a white maid headband over her head, with red lipstick as a cosmetic accessory.

(?) "Welcome home Sirzechs-sama and Serafall-sama" said the white haired beauty with a stoic expression.

(Sirzechs) "I 'am back Grayfia" Sirzechs replied to the beautiful maid.

(Serafall) "Nice to see you again Grayfia-tan" said the air head devil.

(Grayfia) "And welcome back too Paradox-sama" Grayfia said with much respect.

(Paradox) "It's good to see you again Grayfia, you look lovely as ever." He said with his usual tone.

Grayfia then look at the new comer, for a few seconds she just stared at Ben and said…

(Grayfia) Sirzechs-sama is this…

Sirzechs nodded and then Grayfia immediately bowed to Ben.

(Sirzechs) Ben I would like you to meet my lovely wife Grayfia Lucifuge.

(Grayfia) "Greetings mighty Ben Tennyson you honor us with you visit." Said Grayfia with much the same tone he gave Paradox.

Ben was really wondering why they keep saying mighty to him.

(Ben) Um Sirzechs why did Miss Grayfia say mighty addressing me and come to think of it you did too back in my world?

Grayfia just gave an unknowing glance to Sirzechs that he knew what it meant.

(Paradox) "Well explain everything in the manor Ben so please be patience" Paradox explained to Ben while the intention of saving Sirzechs from Grayfia's wrath.

**Gremory Estate - Parlor**

After that little Introduction was over, Grayfia led them to the manor parlor and immediately left to gather the refreshments. Then the room's atmosphere change to one of seriousness.

(Paradox) "Now with all that settled, Sirzechs if you please."

(Sirzechs) "Of course" Sirzechs reply to the time walker. "Now Ben as you know there is a crisis in this world that needs of your assistance, normally letting other beings not from our world get involve with affairs of other realities should be avoided…" he posed for a brief moment then continued "but with the current predicament were left with no choice but to ask for specifically your help Ben Tennyson."

Ben took in on what Sirzechs said before speaking.

(Ben) "I get the problem but why me specifically?" ask with a bit of confusion on why him.

(Serafall) "Because you beat that mean dragon Ben-tan" said Serafall with smile on her face.

(Ben) "Dragon?" then he tried to remember if he ever fought any dragon but he only remembered saving one, never beating one.

(Paradox) "She means the Diagon Ben." Paradox replied to the confused Ben.

Ben was surprised that being from other world knew that he slayed the Diagon.

(Ben) "How?"

(Sirzechs) "Many worlds that the Diagon conquered felt that the power griping their world had vanish and they knew someone had slain him, they sent their kind in search where the last location the Diagon was and what they saw was you, for that moment they knew you where the one who killed their conqueror and freed them." then Paradox continued the conversation.

(Paradox) "The news spread like wild fire to countless dimensions which gave you the titles such as **The Hero**, **Liberator of worlds** and the **Divine Slayer**.

(Ben) "Wow! I knew I was famous but I never knew I was this big of a celebrity." Ben was amazed on how many worlds see him, sure he beaten the Diagon but still…

(Sirzechs) Well Ben it's not every day someone can match let alone defeat one of the three divine dragons.

(Ben) "Oh rea…HUH THREE!" he burst out of his seat on what Sirzechs said "The hell do you mean three?!"

(Serafall) "Like Sirzechs said Ben-tan three, there are two other beings that rival the Diagon." Serafall responded to the hectic boy and continued. "One of theme is known as the **Apocalypse Dragon**, the **True Red Dragon Emperor God**, **True Dragon**, and the **Dragon of Dragons, the Great Red**and the last of the three is the **Ouroboros Dragon** and the **Infinite Dragon God, Ophis.**

Ben was just stunned too know there where two other beings that can rival the Diagon, he was no **Alien X** but still the Diagon was powerful and if these dragons are as strong as the Diagon no wonder Paradox made Azmuth create the new ultimate system.

(Ben) "No wonder you ask Azmuth to reinstall the ultimate system." He said to the time walker. "If these two dragons are as strong as you say there's no question why you guys chose me."

(Sirzechs) Well Ben the problem doesn't concern the two divine dragons as a whole.

(Ben) "Oh … so who's the big problem?" he asks Sirzechs confused on who or what the main concern is.

(Paradox) "An organization called Khaos Brigade led by **Ophis**." Paradox answered Ben in place of Sirzechs.

(Ben) "I thought the divine dragons weren't involved." retorted by our alien hero.

(Paradox) "Well Ben **Ophis** is more of just a figure head than the leader, the ones pulling the strings are the Old Maou faction and the Hero Faction." Paradox explained to the Confused Ben.

(Ben) So who are these factions supposed to be?

(Sirzechs) "As the Name implies the old Maou faction consist of the descendants of the original devil lords…" then Ben interrupted.

(Ben) Wait I thought you where the Maou's?

(Serafall) "No Ben-tan the original Maou's died many years ago during the Great War…" then Ben once again interrupted.

(Ben) What War?

(Serafall) "Well to sum it up the three great factions the Angels, Fallen Angels and Devils were at war, we fought for supremacy over the planet and during the course of the war all of the original Maou's ended up dead. Our numbers dwindled to near extinction."

Ben was…shocked on what happened upon their kind, sure there was the war but to leave them to such an extent.

(Ben) "I 'am sorry" he said so with a saddened expression.

(Sirzechs) Don't be, we knew what the war would bring and yet we saw it through with the death of our leaders and mass decline on our ranks the war was dismissed yet the faction continued to fight each other through small skirmishes.

(Ben) So how did you replace the old Maou's?

(Serafall) We replaced the Maou's due to our power Level.

(Ben) "**Made Sense"** he thought to himself. "So I assume Sirzechs is the strongest out of the leaders since his Lucifer right?" he asked the red headed Maou.

But then the door opened and reviled to be Grayfia along with a cart full of tea and some snacks.

(Grayfia) I 'am sorry to interrupt Sirzechs-sama but I brought the tea.

(Sirzechs) "Ah thank you Grayfia" he said with a smile.

Then Grayfia started to serve to everyone.

(Serafall) Thank you Grayfia-tan.

(Paradox) As always your tea is the best I ever had tasted in my Travels Grayfia-san.

(Ben) "… This is delicious." He said in awe.

Grayfia just smiled and bowed then stood right next where Sirzechs was sitting. Sirzechs then drank some of his tea and continued with the conversation.

(Sirzechs) "As for your question Ben, yes I' am the strongest out of the Yondai-Maou along with Ajuka Beelzebub. Together we are known as the Crimson and Azure (He was called the Blue Satan but I thought I'll go with Azure because its sounds cooler.) Satan." He told Ben of the title that was given to him and Ajuka.

(Ben) So who's the last of the Maou's?

(Paradox) That would be Falbium Asmodeus

(Ben) So where are they now?

(Sirzechs) "Well Ben we haven't told Ajuka yet because he's … kind of an inventor freak and if he sees the omnitrix." Ben just nodded remembering back on Primus what Sirzechs mention about Ajuka. "As for Falbium he does know you're here but he's kind of a lazy ass Ben he doesn't get up much often even for important meeting…" Sirzechs just looked at Ben and he noticed he was just staring at him "hahahah…." He just chuckled nervously.

(Ben) "Are all the Maou's like this?" he asked Grayfia while she sighed. "I take that as a yes."

(Paradox) "Were getting off topic, Sirzechs I think you forgot to mention one important fact?" Paradox told Sirzechs with a knowing smile.

(Sirzechs) "Yes of course." He then turns to Ben with a soft yet sad smile. "Ben I don't know if it would affect you but…" he paused for a moment then said. "god is dead."

Ben eyes slightly widened for a moment then asked.

(Ben) "The Hebrew god?" he asked on which god died for Ben thought if their world devils and the likes existed then other gods from different myths existed as well, the nod Sirzechs gave to Ben just confirmed it.

(Serafall) "You don't look to surprised Ben-tan" she asks with a bit of concern and surprise.

(Ben) "Well to be honest with the story about the Great War and the death of the original Maou's it's not really hard to piece together the puzzles." He said with a confident and calm tone which took back the 2 Maou's and one maid for a brief moment.

(Paradox) Now with the history lesson is over let's go the main topic which is Ben's mission.

(Sirzechs) "R…right, Ben we need you to be part of my sisters peerage." He said with a smile yet a stern voice.

(Ben) Peerage?

(Serafall) "Think about it as chess Ben-tan, a peerage consists of former humans that was reincarnated to devils through a system that Ajuka invented called Evil Piece system." The cute Maou explained to Ben.

(Ben) "So it's a method to heal the major decline of you race faced during the Great War and the peerage's are like chess pieces that consist of 8 pawns, 2 bishops, 2 rooks, 2 knights, a queen and a king." Ben didn't like the idea of turning humans to devils but he couldn't blame them their race was near extinction and they must have been desperate.

(Sirzechs) "Right you are Ben, your mission is to protect my sister and the only sure way you can do that is to be part of her peerage, so you will be attending the same school as her."

(Ben) "I guess she has an important part with the fate of your world I guess." Sirzechs just nodded to Ben's statement. Then the last part of Sirzechs statement came to Ben.

(Ben) Wh… school OH NO HELL NO! I' AM NOT GOING BACK TO THAT DEATH TRAP NO! NOT A CHANCE!

(Paradox) "Ben please calm down." Then Ben breathed slowly until he calmed downed."Better?"

(Ben) "Yah…" replied by our hero.

(Serafall) "I guess he had bad experiences with school huh?" the petit Maou said with sweat drop anime style to professor Paradox.

(Paradox) "Now Ben you WILL be attending Kuoh Academy starting tomorrow." With that said Ben just cringed and then realized.

(Ben) "Wait where will I stay" he said with confusion to Paradox.

(Paradox) "I' am glad you asked." He said with much amusement, and then Paradox took out his pocket watch and the familiar blue light appeared.

The next thing he knew he, Sirzechs, Serafall and Paradox was somewhere within a residential area, he then noticed he was in front of a six-story house.

(Ben) "Paradox is this… my home…" he said with a shocked expression (this is the Hyoudou residence after renovation.).

(Paradox) "Yes Ben, Me, Sirzechs and Serafall took the liberty of preparing your accommodation while you stay here." Paradox explained to Ben.

(Ben) Don't you think it's a little bit too much?

(Sirzechs) It was no trouble at all Ben don't think to hard about it.

(Ben) "Well if it's all right with you." He said while scratching the back of his head.

(Sirzechs) "After all you are my future broth…" Sirzechs was about to finish his sentence until.

(Paradox) "Cough!, Sirzechs no spoilers now" Paradox retorted to Sirzechs.

(Sirzechs) "Sorry" he replied to the Time walker.

Ben was curios on what Sirzechs was about to say it.

(Ben) "**It sounded he was about to say brother?**" he was in thought until Paradox…

(Paradox) "Ben all you need during you stay is inside the house now gets some sleep you have a big day tomorrow." The time walker said too our alien hero as they were about to leave until…

(Ben) "Wait how will which ones your sister, what's her name." Ben shouted to the top of his lungs.

(Sirzechs) "Her name is Rias Gremory and you'll recognize her when you see her, good luck Ben and please protect her." He said those final words until the blinding blue light overwhelmed Bens eye's and the next thing he knew they were gone.

(Ben) "Sigh guess I'll just find out tomorrow." With that said he entered his new house and prepared for bed waiting the sure hectic day tomorrow.

**(I'll skip the part on how socked Ben was when he entered his home just think of it the same way Issei was when Rias renovated his home in the Light Novel)**

**Unknown Location:**

(?) It seems that time walker has brought Tennyson to this plan of reality.

(?) Yes he has **Chronian;** Paradox was always the meddling type.

(Chronian) Should we tell the others from Khaos Brigade?

(?) No not yet, the moment will be presented to as in due time.

(Chronian) As you say.

(?) Soon Tennyson soon I'll have your throat but before all that I'll crush your love before your very eyes once more… Rias Gremory…

The next day

**Tennyson Residence**

(Ben) "When Paradox said they got it covered they REALY MEAN IT!" he was really surprised he had all the niceties and the forged document he needed.

Now our alien hero is on his way the most hellish place on earth ….. School. When he arrived all of the students were staring at him he heard their conversation about him the girls were saying how cute he was and that brought a small blush on his face but for the males they where saying "Die you pretty boy, about how unfair the world was and more gibberish like that" and well he didn't care the slightest. He arrived at his designated classroom and was greeted by his home room teacher and to his surprised it was… a freaking loli teacher like you see on those anime's (imagine Douraku Utage from Noucome)

(Utage) Ah you're the new kid Tennyson Ben right?

(Ben) Uh yah… are you the Sensei?

(Utage) Hard to believe?

Ben just laughed nervously

(Utage) Well come on in and introduce yourself.

They both entered and once Ben introduced himself he was bombarded with many questions like "what's your hobby, do you have a girlfriend and WHY DID YOU HAVE TO TRANSFER HERE!" with all that over Utage told Ben to sit on one of the seats near the window, when Ben was about to sit down he saw her… she was the most beautiful girl he lay his eye's own she was at her late teens with a buxom figure, a light skin tone, and blue-green eyes. Her most distinctive feature is her long, crimson red hair that reaches down to her thighs, with a single hair strand (known in Japan as ahoge, or idiot hair) sticking out from the top. Her hair also has loose bangs covering her forehead and side bangs framing her face.

When Ben looks at her eyes and he knew at that moment it was her, the woman he was tasked to protect she was…

(Ben) **Rias Gremory**.

*Chapter End*


	3. Interlude-Distant past left forgotten

I do not own Ben 10 and Highschool DxD.

All are owned by their respected owners.

**Interlude:**

"**Ben's Dream – Unknown Location."**

Ben could not believe on what he's seeing, he was in an unfamiliar city, it engulfed in fire, he can hear screams of pain, horror and death. He saw body's burned to unrecognizable features; bodies litter the streets it made him sick to his stomach. He wanted to help the surviving people but he found himself unable to move, he can't believe it … no he doesn't want to believe it.

(?) RIAS!

He heard someone scream when he looked for the source of the scream he was shocked, he saw himself holding someone, Ben tried to focused his eyes on the girl and to his horror he saw Sirzechs little sister Rias Gremory but he saw that she had a massive hole between her chest, Ben couldn't believe it she was dead.

(Dream Ben) I'll make you pay! **I'll make you paaaaaaaaayyyyyyyyyyyy!**

Ben then turned his gaze to whoever his dream counterpart was looking at and what he saw was a being made of pure black metal, he seems to have short pointed horns on his head and a visor emitting an eerie glow of red (Imagine Ultron from Avenger's heroes of tomorrow but black and more sleek).

(Dream Ben) **I'll make you paaaaaaaaayyyyyyyyyyyy! BOOSTED GEAR BALANCE BREAKER.**

Ben then saw a red gauntlet appear in his right hand, and the next thing he saw arcs of fire enveloped him and heard the gauntlet say…

(Boosted Gear) **Welsh Dragon OVER BOOOSTER!**

The next thing Ben saw was his counterpart covered in red dragonic armor and he heard some short of chant from him…

(Dream Ben)** I, who is about to awaken,**

**Am the Heavenly Dragon who has stolen the principles of domination from God**

**I laugh at the "infinite", and I grieve at the "dream"**

**I shall become the Red Dragon of Domination**

**And I shall sink you to the depths of the crimson purgatory!**

Ben saw the transformation his counterpart it possesses claw-like growths on the hands and feet, as well as horns and a fanged mouth on the helmet, the mouth being capable of delivering deadly bites to opponents. He then heard an unholy roar from his counterpart and charged to the unknown being and with a flash of crimson light the dream ended.

Ben woke up he was sweating and panting from the nightmare he had he tried to piece it all together and just concluded it as a random dream, but in the back of his mind it was trying to say to him… **it was real.** In the end Ben just tried to forget the nightmare and return to his slumber and hope that nightmare never happen again.

**Unknown location**

(?) Hmmm…

(Chronian) What's the matter?

(?) It seems Tennyson received some memory from his parallel self, most intriguing.

(Chronian) Will it cause problems to our plans?

(?) For know no let's just let things go naturally, how's your observation with this world **Vanishing Dragon?**

(Chronian) Bah his as strong as the other one but he is more of battle freak than the one in our reality.

(?) Good just keep an eye out from him.

(Chronian) Right.

The Chronian left with a flash of violet light

(?) Oh I wanted see that face of yours Tennyson when those memories went to you (Laughing) but I'll let you suffer little by little until I'll kill her in front of you again.


	4. Chapter 3

I do not own Ben 10 and Highschool DxD.

All are owned by their respected owners.

Alright Chapter 3 ready and as always I hope you enjoy this!

*Spoiler*

The long awaited part Ben and Rias's encounter and in part 2 the unveiling of Ben's sacred gear (boosted gear). Also in here Ben will go on a date with Raynare but she won't try to kill Ben but plead to him to join the fallen Angel side but off course he would decline, well that's it for now on with the story!

*Spoiler*

Chapter 3: The weird encounter part 1

**Tennyson Residence:**

Ben was in a predicament, he doesn't know if he should be very happy or pissed and why is he like this? Apparently HIS new master the number one beauty of Kuoh academy Rias Gremory is sleeping with him in BED! But the thing that bothers him the most is she's FREAKING NAKED!

(Ben) "Sigh how did it end up like this?" our hero said trying to put the pieces together.

**Kuoh Academy – six days ago**

(Ben) "Rias…Gremory…" he was just staring at her like someone he hasn't seen in a long time.

(Rias) "Yes?" she asked him wandering what's wrong.

Ben just continued to stare at Rias not budging an inch.

(Rias) "What is it?" a small blush appeared on her yet in her mind "**Does he sense that I' am a devil, I can fell power from him almost limitless. I can sense a faint power of… a dragon!? But the other is not familiar and it's so diverse!"** For a brief moment Rias saw something she couldn't understand what it was, yet that thing gave of…**Power**, **Absolute Power**, she shuddered yet it was not visible to other.

(Utage) "Would you two love birds quit gawking at each other!" while she kicked Ben right in the gut.

(Ben) "Guk!" then Ben fell to his knees while clenching his stomach the he lost consciousness.

(Utage) "Shit… some one's got to bring him to the infirmary, Hoy Rias, Akeno bring the idiot to the infirmary would yah."

(Rias) "Yes…Sensei." The red headed beauty responded with surprise in her tone.

(Akeno) "Fufu of course sensei" said the raven haired beauty.

Akeno Himejimabest friend of Rias Gremory and the Second of the top 4 Beauties of Kuoh Academy, Queen of Rias's peerage she appeared to be a buxom young woman who is around the same age as Rias with very long black hair and violet eyes. Her hair is usually tied in a long ponytail, reaching all the way down to her legs with two antennae sticking out from the top and sloping backwards, with an orange ribbon keeping it in place. Like most of the girls at Kuoh Academy, she wears the customary Kuoh Academy girls' school uniform, along with black knee-high socks, she is also… ah Sadist.

(Utage) oh and don't tell the nurse I did it Kay!

Both Rias and Akeno nodded to Utage and proceeded with Ben to the infirmary while the guys shouted **"You Lucky Bustard!"**

5 minutes later…

**School Infirmary**

They layed Ben on one of the beds and the 2 Onee-samas just stared at him trying to figure out the power they were sensing. Then their eyes landed on his left arm more specifically the omnitrix.

(Rias) Is this some short of sacred gear?

(Akeno) "I don't know? But it's undoubtedly powerful." She then proceeded to touch the omnitrix until the dial turned yellow.

(Omnitrix) **"Unknown DNA Detected."** Said the assumed sacred gear, both stepped back due to the sudden voice. Then the omnitrix just like with Serafall enveloped Akeno with a yellow light, **"Unknown DNA recorded, transformation now available."**

Then some short of hologram appeared and it showed a siluet of a fallen young fallen angel.

(Akeno) What do you think it is Buchou?

(Rias) I don't know? Try pressing it.

A soon as Akeno did a bright green light overwhelmed their sight and the once boy known as Ben Tennyson changed to a young fallen angel, his features was a handsome man, possessing deep-blue eyes, messy silver hair and of course 3 pairs of black feathered wings and there was the same symbol of his watch right in the center of his chest. Both Rias and Akeno where… drooling over the sudden change from his normal form to a drop dead handsome guy. Both in their minds had imagined all the things they would do to him at this moment, only when Ben started to wake up they escaped from all the sinful thoughts that went inside them.

(Ben) "Groan… where I'm I?" He then turned his eyes to the only people in the room with him. "Miss Rias? What are you doing here?"

(Rias) "You suddenly fainted in class and Utage sensei told us to bring you to the infirmary Ben-kun." She said with a sweet smile.

(Ben) "Ben-kun? Oh right Japanese honorifics." He then turned to the other girl in the room. "And you are?"

(Akeno) "Nice to meet you Ben-kun, my name is Akeno Himejima but please just call me Akeno." She said with a bow.

(Ben) "Ah thank you Akeno-san" he said while remembering the proper honorific.

(Rias) "Well then Ben-kun can you explain to us why is a Fallen Angel doing in my territory?" she said with slit venom in her words.

(Ben) The hell are you saying Rias-san

(Rias) "Don't play dumb, just look at you,you're clearly a Fallen Angel." She shouted to our alien hero.

Ben was confused on why they where accusing him on being a fallen angel, he felt something on his back. The look he gave was something quizzical he then put his hand on the middle and felt the omnitrix like all in his transformation. He proceeded to tap on the omnitrix and the same blinding green light appeared and thus returned to normal. Both Rias and Akeno were stunned on what has happened.

(Rias) How? You're completely human again?!

(Ben) Ah… well you see it's hard to explain.

(Rias) "Really now?" she said with narrowed eyes. "Well if you're not a fallen angel then I assume that your sacred gear transforms you to any species it comes in contact with you.

Ben raised an eyebrow thinking how they knew about that function of the omnitrix unless…

(Ben) "Akeno-san did you touch the omnitrix by any chance?" asked our alien hero.

(Akeno) "So it's called the omnitrix and for you question Ben-kun yes I did after it scanned mewe saw a small green figure pop out and well we…"she answered the teen hero then trailed off until Rias interfered.

(Rias) Akeno slammed the center of the omnitrix and you turned to a fallen angel.

(Ben) Ah I see well I'm sure you have a lot of question so can it wait maybe tomorrow after school?

Rias pondered for a while but just gave in to his request.

(Rias) "Sigh…" she sighed then smiled to Ben. "Fine I'll send someone to tomorrow after class okay."

(Ben) Great! With all that settled lets go back to class.

The two beauty's nodded and headed off too class.

The day just past and Ben was headed home until the omnitrix beeped saying…

(Omnitrix) "Incoming transmition, Sirzechs Lucifer."

(Ben) Sirzechs? Omnitrix accept transmition.

(Omnitrix) "Accepting." Responded by the alien device with the same voice of Ben.

(Sirzechs) "Ah Ben how was your first day?! Did you meet with Rias already?! How is she?!" the Crimson Maou asked with much excitement.

(Ben) "Okay Okay calm…" Ben was not able to finish his sentence when he heard a SMACK! Sound from Sirzechs end of the line.

(Sirzechs) "Ouch…that hurt Grayfia.' He responded with a whiny manner of speech to Grayfia.

(Grayfia) "Sirzechs-sama please keep the conversation with Ben-sama brief as possible." She said with her usual stoic tone.

(Sirzechs) "Aw alright fine! (Cough), Ben there were reports of giant blue robots coming out of nowhere at random places through some short of dimensional gate, they didn't destroy or take anything from the locations they have been but they seem to be searching for something or someone." Said the Maou full of seriousness.

Ben had a good idea who they were.

(Ben) What do they look like?

(Sirzechs) They had a big wheel to ride on, a round waist and a circular head. He has long arms and claws which appear to have a red glow surrounding them.

Then with that it was obvious who they were.

(Ben) "Those are Computron's robots from **Dimension 12, **don't worry Sirzechs I'll take care of this they're not that dangerous if dealt properly." He said those words to assure Sirzechs that everything will be fine.

(Sirzechs) Please do Ben and keep an eye out for my sister and her peerage tonight.

(Ben)Why? What's tonight?"

(Sirzechs)They received a request to eliminate a stray devil.

(Ben) Stray Devil?

(Sirzechs) To put it simply they are devils who left their masters and went rouge. They are moved by their blood lust and eat humans.

Ben was shocked at this revelation he wanted to throw up but stayed composed.

(Ben) "Alright Sirzechs I'll look after Rias and that stray while I'm at it." Ben said with much hatred on the last part of sentence.

(Sirzechs) Good luck Ben.

(Omnitrix) "Transmition ended." Announced by the omnitrix.

(Ben) "Well…guess it will be a busy night." He said with a lazy tone.

**Later that Night – Random location within the residence.**

Ben was walking on the streets, his attention on his surrounding battle ready for any kind of ambush but as the hours go by Ben was…getting restless he didn't see any stray devils or Computron's goons until he heard an explosion from a warehouse.

(Ben) "Guess its Hero Time!" Ben proclaimed and reaches for his omnitrix then cycled to his chosen form, then the familiar green light enveloped him.

**Warehouse**

Rias and her peerage where being overwhelmed by Robots! She could not believe it robots! Like from those sci-fi novels and movie's. They supposed to exterminate a stray devil but what the found was the stray devil mutilated by this machine's.

(?) GUH!

Rias heard a wail from one of her peerage he is a handsome young man with short blonde hair and grey eyes. His name is Yuuto Kiba.

(Rias) "Yuuto!" she screamed with much worry to her knight.

Then lightning struck the machine, fell and exploded. Rias then turned to her friend Akeno.

(Rias) Good job Akeno!

(?) AHHHH!

Rias heard another scream this time it was a petite girl around 15 years of age with white hair and hazel eyes. At the front, her hair has two long bangs going past her shoulders and several loose bangs hanging over her forehead, while the back has a short bob cut. She also wears a black cat-shaped hair clip on both sides of her hair, she like the group wears the Kuoh Academy girls' school uniform, without the shoulder cape.

(Rias) Koneko! Tsk!

She saw Koneko being attacked by three no… five of those things.

**Smack!**

One of those robots used its wipe like arm on her and she was sent crashing to a wall and Koneko's conciseness left her. Rias used her power the **Power of Destruction; **theshe inherited from her mother's side the Baal clan.

Rias was able to destroy one of the robots but now the remaining ones turned to her. She froze, she was terrified this thing outnumbered them and only she and Akeno were able to deal with them.

(Rias) "**Is… is this it? We're going to die just like that?" **she said within her thoughts in a terrified state. "**Please someone, Onii-chan, Grayfia-nee…" **the images of Sirzechs and Grayfia appeared in her mind but a third person's image followed it was some she barely knew, someone she has just meet at school, she didn't know why he came up but she felt that **HE **will be there for her… **"BEN!" **she yelled withall her strength.

**BOOOOMMM!**

Rias opened her eyes to see who caused the explosion, what she saw baffled her it was big; it has a yellow-armored body and looks much like a robot. His head is similar to a Greek Corinthian helmet with two ears on it giving him the appearance of an armadillo. It has a gray tail and jackhammer parts on his elbows, wrists and hands.

The creature then continued to pulverize the machines that where coming at her, the creatures arms vibrated while hitting the said machines and leaving nothing but scrap metal.

She didn't know who or what it was and why it was helping them. The creature faced her and said "You okay Rias?" Rias was frightened, confused and any kind of emotion in this kind of situations her eyes drifted to the middle of the creatures chest and she saw the very same symbol of mysterious device she saw early at school and she knew who this creature was…

(Rias) Be…Ben!

(**Armodrillo**) Yah it's me but in this form call me **Armodrillo!**

**Chapter End**


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